Control system for air conditioning apparatus



Jan. 31, 1939. R J E|$|NGER 2,145,298

CONTROL SYSTEM FOR AIR CONDITIONING APPARATUS Filed July 25, 1936 WITNESSES: I INVENTOR 9 )0 ?,%4M unowu Jhsmcasa.

Patented Jan. 31, 1939 UNITED STATES PATENT OFFICE CONTROL SYSTEM FOR AIR- CONDITIONING APPARATUS of Pennsylvania Application July 25, 1936, Serial No. 92,489

'1 Claims.

My invention relates to a control system more particularly to a control system for air conditioning apparatus comprising a plurality of air coolers having a common limited supply of cooling fluid, and it has for an object to provide an improved control system.

A more particular object is to provide a control system which eifects a maximum limit on the number of air coolers in operation at any one time, that is, the number supplied with cooling fluid, and which permits any one air cooler, or any combination of air coolers not exceeding said maximum limit, to be operated at one time. I

In accordance with my invention, I provide mechanism responsive to the number of air coolers in operation and effective to render the remainder inoperative when the maximum number thereof are in operation. Preferably, the mechanism includes a circuit for each cooler and a set of contacts in said circuit for each combination of the maximum number of' the other air coolers. The contacts of each set are in parallel with each other and the several sets of contacts are in series. Thus, a circuit is maintained open when 7 all the parallel contacts of any one set are open, which occurs when the maximum number of air coolers is in operation. Means for effecting operation of the cooling fluid supply means when any air cooler or coolers are in operation may also be provided,

The subject-matter of the present application is broadly covered by the claims in the patent of Raymond J. Ridge, No. 2,048,711, issued July 28, 1936, and assigned to the Westinghouse Electric & Manufacturing Company.

These and other objects are effected by my invention, as will be apparent from the following description and claims, taken in connection with the accompanying drawing, forming a part of 40 this application, in which:

The single figure is a diagrammatic view of my novel control mechanism.

Referring to the drawing in detail, I show air cooling. devices II, I2, I3 and I4, which may be disposed, for example, in rooms or enclosures l5 to I8, respectively. Each air cooling device may include, as shown, a cabinet I9, a cooling coil or evaporator 2| disposed therein, an expansion valve 22, a fan 23 for circulating air into the cabinet, over the cooling coil and into the room. The expansion valve is of any suitable type known in the art, such as a thermostatic expansion valve 55 rator to maintain the superheat thereof substantially constant. A motor 24 is provided for driving the fan 23."

The several 'evaporators are supplied with liquid refrigerant by a refrigerating mechanism 24, commonly termed a refrigerating or condensing unit, including a compressor 25 driven by a motor 26, a condenser 21 and a liquid receiver 20. The liquid receiver 28 is' connected to the inlet ends of the several evaporators through a conduit 20 and branch conduits 3|, while the inlet of the compressor is connected by a suction conduit 02 and branch conduits 33 to the outlet ends of the several evaporators. The refrigerating mechanism operates in the conventional manner, the vaporous refrigerant being compressed in the compressor 25, condensed in the condenser 21!, collected in the receiver 28 and delivered through the conduits 29 and 31 to the evaporators in which it is vaporized in extracting heat from the air passing thereover. The vaporized refrigerant is withdrawn from the several evaporators by the compressor through the conduits 33 and 32, and

again compressed.

Air cooling apparatus of the type so far described may sometimes be used in cases where only a limited amount of cooling at one time is required but where such cooling may be required in different rooms. In such cases, it is expedient to provide a refrigerating unit 24 of less capacity than the total capacity of the air coolers. For the purpose of disclosing my invention, I have assumed that it will be desired normally to cool but two rooms and that the refrigerating unit 24 has a capacity to supply liquid refrigerant for satisfactory operation of two air coolers. Each air cooler may have a capacity, for example, to extract 12,000 B, t. u.s per hour and the refrigerating unit 24 may have a capacity to supply liquid refrigerant for extraction of 24,000 B. t. u.s per hour.

The present control system provides for the control of the air cooling apparatus such that the air coolers may be individually controlled and any one or any combination of room coolers whose capacity does not exceed the capacity of the refrigerating unit 24, may be operated at one time. The control mechanism includes a handoperated double-pole switch 34 for each air cooler, the first pole controlling the supply of liquid refrigerant and the second pole providing operation of the fan 24. A second switch 35 is also provided for each air cooler for effecting operation of the fan 24 without providing for cooling. One terminal of each switch pole is connected through a conductor 36 to a line conductor L a conductor 38 to the line conductor L The otherterminalsofthefirstpoleof theseveral switches 3 are connected through thermostats 3! to circuits H to I, respectively. Solenoids A to D are connected in the circuits ll to 41, re-

7 m A solenoid G5 is connected in shunt with each of said solenoids and. operates a valve Ii in the branch supply conduit St, for the purpose of controlling the simp y of liquid rah-igerant to the individual air cooler. The solenoid opens the valve when energized and closes the valve when dcenergized.

For the purpose of preventing operation of more than two air coolers atone time, the circuits H to ll are provided with contacts operated by the solenoids A to D, as will now be described. The reference characters of the contacts contain the letter designating the solenoid by which they are operated. There is provided in each of said circuits, a set or pair of contacts arranged in parallel with each other for each combination among the remaining coolers of the maximmn number to be operated at one time, in this case two. As the contacts of each set are in parallel with each other, when a combination of a air coolers corresponding to the maximum numher is in operation, the circuit is opened by the parallel contacts of one set. The several sets of contacts are in series with each other, so that any one of the several possible combinations is eflective to open the circuit, As shown on the drawing, and as will be described, some of these contacts are preferably common to a plurality of sets of contacts.

The circuit 4! has one branch ll extending through contacts 13 and a second branch 48 containing contacts 0 and D in series. The circuit 2 has one branch 5 containing contacts Al anti a second branch 5% having contacts C and D Beyond the contacts first mentioned, the mveral 5 branches I to 5! join a conductor 5!, through which the circuits ti and 42 extend in common to the line conductor L The conductor 5! contains contacts (I and 1) arranged in parallel. The circuit 43 has a branch 53 containing con- 0 tacts A and B and a second branch 5 containing contacts D The cirmnt M has a branch 55 containing contacts C and 'a second branch 56 containing contacts 5. and B Beyond the contacts just mentioned, the branches 53 to 5 5 are connected to a conductor 5! through which the circuits 3 and M extend in common. The conductor 51 contains contacts A* and 3* arranged in parallel, and joins the conductor 52 to connect with the line conductor Ll.

m It will be noted that each circuit contains a Set of parallel contacts for each combination of two of the other air coolers, so that it is opened whenever two other coolers are in operation.

- Referring to the circuit H, for example, the con- 5 tactsB andC areinparalleLasarethecontacts B and D, so that if either the cooling devices l2 and E3 or the cooling devices It and ll are in operation, both of the branches I! and. ll will be opened to prevent closing of. the cir- 7. unit ll. Operation of the third pofible com- -hination, comprising coolers I3 and. It, opens contacts C and D so that ention of the circuit ll is prevented. Similarly, the circuit 42 contains contacts A and C in parallel, and the 15 contacts A and D in parallel. The contacts (FamiD-aretothedrcultmliamifl, sothathothaircoolers llandllarerenderui inoperahlewhenaircoolers i3 and Marcia operation. Iikewisethedrcuihflandflecch. containapairotparallelcmtactsforcschpos- 5 siblecmmhinationofitwootheraircoolernwmill hereadilyseenfimnthedrnwing.

Thesolenoidshtonalschavecontnctsh to l.) which contacts are in parallel. Witheachotherandalreazrrangetltoheclosed g whentheassociatedsolenoidis These contactscloseacircuititwhichconnectsthe motor litolinecomluctorsllfanclh. Theline conductors B and L may he in common with the line conductors I. andI-F. u

The operation of the above described amatusisasiollowszfiirccolingofnnymeofthe roonrsmaybeobtainedbychnngtheswitchfl. For example, that it is desired to obtain coolinginroonr t5,theswitchflofithatmomg is closed and if the temperature is above the desired temperature, the t 3! closes its contacts to complete the circuit It. Assume also that no other cooler is in operation. All of the contacts B C D C and. IF are so a that the M is completed- The aiming: of the circuit H energizes the solenoid E5 of the air cooler H to open its valve H, and. also energizes the solenoid A to close: the contacts A Hie latter contacts energize the motor 25 to a efiect operation of the refrigerating unit it for supplying the liquid refrigerant Operation 01 the air cooler ll thus provided.

the temperature in the room [5 is reduced to the value, the thermostat I! opens the circuit ll, closing of the valve 46 and down of the refrigerator 2i. Intermittent operation of the cooling device [I is eiiected to maintain the desired temperature. The fan 24 operates continuously for ventilation, but cooling; is not except a when. is admitted; to the evaporater 2t.

Assume now that air coolers it and; M1 are to be operated. switches 31 are closed, and assuming the to be above the value to be the circuits ME and (J3 are completedandthe The. control is now in the condition shown onthedrawingjnwhichthecircnitsfl and are completedamlinwhich the circuit His" openedatthecontacts h andc and the circuitflisopenedatthecontactsfiandcfisc thatoperationoftheaircoolers Hand ilk prevented. aircoolers llandlioperateaszdcsmeadr ahcoolerbeingundercontrolofitst SSandtherefIigeJntingunitHm longaseithcrtatcalhfor cooling.

Whenoperationofeithercfithcaircooling devices II and. I3 ceasendueeitherto';

oftheswitchflorthetl9,eitherof llandlimaybeoperated. Forexammiftheswitchflcndthennostati! oftheaircoolerflareclosedwhmthe ttoitheaircooler Hopenstheamnt I, th an: 'tionofthesolenoid Apemib thecontactsA toclose. clowdtoeliectoperationoftheaircooler i2. Theaircooler llthencannotbeagainopuated aslongasmmmmrrunumm operation.

Whilennneofthecontactsare-to morethanonesetofcontactnituillhenoted that,inthecirmiitoieachaircooler,thereis a set of contacts arranged in parallel for each combination of two of the other air coolers. The several sets of contacts are, in effect, arranged in series, since any one set is adapted to open the circuit.

It will be apparent that the control system may be extended to control a greater number of air coolers and to provide for operation at one time of a maximum number of air coolers greater than two.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desired, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. In a control system for cooling apparatus including at least three evaporator elements and common means for supplying liquid refrigerant thereto, the combination of meansfor selectively admitting liquid refrigerant to said evaporator elements, and means responsive to operation of a predetermined plural number of evaporator elements of various combinations for rendering the remaining evaporator element or elements inoperable.

2. In a control system for cooling apparatus including at least three evaporator elements and common means for supplying liquid refrigerant thereto, the combination of a switch associated with each evaporator element for controlling the supply of refrigerant thereto and for effecting operation of the refrigerating unit, and means responsive to operation of a predetermined plural number of evaporator elements of various combinations for rendering the remaining evaporator element or elements inoperable.

3. In 'a control system for cooling apparatus including at least three evaporator elements and common means for supplying liquid refrigerant thereto, the combination of a switch associated with each evaporator element for controlling the supply of refrigerant thereto and for effecting operation of the refrigerating unit, and means responsive to operation of a predetermined plural number of evaporator elements of various combinations for rendering the remaining evaporator element or elements inoperable, said control system permitting simultaneous operation of any combination of evaporator elements not exceeding said predetermined number.

4. In a control system for cooling apparatus including at least three evaporator elements, common means for supplying liquid thereto, and at least three valves for controlling the flow of liquid refrigerant from said supply means to said evaporator elements, the combination of an electrical circuit for each valve, means for energizing each circuit at will, a relay for each circuit including a solenoid connected in the circuit and contacts in the other circuits, each circuit having therein a set of parallel contacts for each combination of a predetermined maximum number of other circuits, the several sets of each circuit being in series, whereby when the predetermined number of circuits is energized the remainder are rendered incapable of being energized.

5. In comfort cooling apparatus, the combination of at least three air cooling elements, means for selectively supplying cooling medium to said elements, and means responsive to the operation of any air cooling elements of a predetermined plural number less than the total number of elements for rendering the remaining element or elements inactive.

6. In comfort cooling apparatus, the combination of at least three evaporators for cooling air, a fan associated with each evaporator for translating air in heat exchanging relation therewith,

means for selectively supplying refrigerant to said evaporators, and means responsive, to the operation of any evaporators of a predetermined plural number less than the total number of evaporators for rendering the remainder inactive.

7. In a control system for cooling apparatus including at least three evaporator elements, the combination of an electrical circuit associated with each evaporator element and adapted to be energized concurrently with operation of the evaporator element, means associated with each evaporator element for initiating and terminating operation thereof, the action of the last-men- ,RUDOLPH J. EISING. 

